Molecular analysis of the prevalent microbiota of human male and female forehead skin compared to forearm skin and the influence of make-up

Aims: To compare the bacterial diversity of two different ecological regions including human forehead, human forearm and to estimate the influence of make‐up. Methods and Results: Twenty‐two swab‐scraped skin samples were analysed by profiling bacterial 16S rRNA genes using PCR‐based sequencing of randomly selected clones. Of the 1056 clones analysed, 67 genera and 133 species‐level operational taxonomic units (SLOTUs) belonging to eight phyla were identified. A core set of bacterial taxa was found in all samples, including Actinobacteria, Firmicutes, and Proteobacteria, but pronounced intra‐ and interpersonal variation in bacterial community composition was observed. Only 4·48% of the genera and 1·50% of the SLOTUs were found in all 11 subjects. In contrast to the highly diverse microbiota of the forearm skin, the forehead skin microbiota represented a small‐scale ecosystem with a few genera found in all individuals. The use of make‐up, including foundation and powder, significantly enlarged the community diversity on the forehead skin. Conclusions: Our study confirmed the presence of a highly diverse microbiota of the human skin as described recently. In contrast to forearm skin, gender does not seem to have much influence on the microbial community of the forehead skin. However, the use of make‐up was associated with a remarkable increase in the bacterial diversity. Significance and Impact of the Study: This study enhances our knowledge about the highly complex microbiota of the human skin and demonstrates for the first time the significant effect of make‐up on the bacterial diversity of the forehead skin.     

Commensal Staphylococcus epidermidis contributes to skin barrier homeostasis by generating protective ceramides

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Artificial skin in perspective: concepts and applications

Skin, the largest organ of the human body, is organized into an elaborate layered structure consisting mainly of the outermost epidermis and the underlying dermis. A subcutaneous adipose-storing hypodermis layer and various appendages such as hair follicles, sweat glands, sebaceous glands, nerves, lymphatics, and blood vessels are also present in the skin. These multiple components of the skin ensure survival by carrying out critical functions such as protection, thermoregulation, excretion, absorption, metabolic functions, sensation, evaporation management, and aesthetics. The study of how these biological functions are performed is critical to our understanding of basic skin biology such as regulation of pigmentation and wound repair. Impairment of any of these functions may lead to pathogenic alterations, including skin cancers. Therefore, the development of genetically controlled and well characterized skin models can have important implications, not only for scientists and physicians, but also for manufacturers, consumers, governing regulatory boards and animal welfare organizations. As cells making up human skin tissue grow within an organized three-dimensional (3D) matrix surrounded by neighboring cells, standard monolayer (2D) cell cultures do not recapitulate the physiological architecture of the skin. Several types of human skin recombinants, also called artificial skin, that provide this critical 3D structure have now been reconstructed in vitro. This review contemplates the use of these organotypic skin models in different applications, including substitutes to animal testing.     

益生菌防治特应性皮炎的研究进展

特应性皮炎(atopic dermatitis,AD)是会反复发作、具有明显遗传倾向性的慢性炎症性皮肤病,发病率逐年增高.AD的发病机制主要为遗传性或获得性皮肤屏障受损引起的皮肤微生态失衡和变应原渗漏,激活对应的炎症反应,造成"屏障受损-炎症反应"的恶性循环.AD的传统治疗方法多采用糖皮质激素和免疫抑制剂,但其副作用的...     

Reflection and penetration depth of millimeter waves in murine skin

Millimeter (mm) wave reflectivity was used to determine murine skin permittivity. Reflection was measured in anesthetized Swiss Webster and SKH1-hairless mice in the 37-74 GHz frequency range. Two skin models were tested. Model 1 was a single homogeneous skin layer. Model 2 included four skin layers: (1) the stratum corneum, (2) the viable epidermis plus dermis, (3) fat layer, and (4) muscle which had infinite thickness. We accepted that the permittivity of skin in the mm wave frequency range results from the permittivity of cutaneous free water which is described by the Debye equation. Using Fresnel equations for reflection we determined the skin parameters best fitting to the reflection data and derived the permittivity of skin layers. The permittivity data were further used to calculate the power density and specific absorption rate profiles, and the penetration depth of mm waves in the skin. In both murine models, mm waves penetrate deep enough into tissue to reach muscle. In human skin, mm waves are mostly absorbed within the skin. Therefore, when extrapolating the effects of mm waves found in animals to humans, it is important to take into account the possible involvement of muscle in animal effects.     

CYLD regulates keratinocyte differentiation and skin cancer progression in humans

CYLD is a gene mutated in familial cylindromatosis and related diseases, leading to the development of skin appendages tumors. Although the deubiquitinase CYLD is a skin tumor suppressor, its role in skin physiology is unknown. Using skin organotypic cultures as experimental model to mimic human skin, we have found that CYLD acts as a regulator of epidermal differentiation in humans through the JNK signaling pathway. We have determined the requirement of CYLD for the maintenance of epidermal polarity, keratinocyte differentiation and apoptosis. We show that CYLD overexpression increases keratinocyte differentiation while CYLD loss of function impairs epidermal differentiation. In addition, we describe the important role of CYLD in the control of human non-melanoma skin cancer progression. Our results show the reversion of the malignancy of human squamous cell carcinomas that express increased levels of CYLD, while its functional inhibition enhances the aggressiveness of these tumors which progress toward spindle cell carcinomas. We have found that the mechanisms through which CYLD regulates skin cancer progression include the control of tumor differentiation, angiogenesis and cell survival. These findings of the role of CYLD in human skin cancer prognosis make our results relevant from a therapeutic point of view, and open new avenues for exploring novel cancer therapies.     

Commensal microbiota regulates skin barrier function and repair via signaling through the aryl hydrocarbon receptor

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Optimisation of skin phototype classification

Understanding individuals' skin pigmentation and photosensitivity is important in judging risk of skin cancer and response to certain treatment modalities. However, individuals with darkly pigmented skin are poorly represented in the widely used Fitzpatrick skin phototype (FST) system. Moreover, the FST system is prone to misuse, as it relies on subjective patient and clinician assessment of skin type, and does not clearly differentiate pigmentation from photosensitivity. By evaluating the key literature surrounding the FST system, its criticisms and proposed alternatives, this review serves to understand how skin phototype classification can be optimised.     

Growth potential of Rana tigerina skin lipids in cell cultures

Summary This study involves the investigation of the lipid composition of the skin of Rana tigerina which has a significant healing capacity. The results indicated that the lipid extract enhanced keratinocyte and fibroblast cell proliferation progressively and were found to be much more efficient in comparison to agents known to cause cell proliferation and to be anti-inflammatory such as hydrocortisone. Cell proliferation was dose dependent and suppression occurred only at very high doses. [³H]thymidine incorporation studies produced the same results. Because proliferation, migration, and differentiation of the basal cells is essential for initiation and progression of wound healing, any agent enhancing their proliferation would hasten the healing process. This paper therefore aims at elucidating the effect of composition of the total lipid extract confirming the efficacy of frog skin in wound healing and thereby providing an understanding of the natural mechanism of healing.     

Recognizing Latinos’ range of skin pigment and phototypes to enhance skin cancer prevention

Latinos in the United States may have the mistaken assumption that their natural pigmentation protects them from developing skin cancer that, effectively, serves as a barrier to Latinos receiving education in primary and secondary prevention of skin cancer. Latino adults of Mexican or Puerto Rican heritage attending community health fairs in the greater Chicago area responded to a culturally informed and sensitive measure for sunburn and tan, which was previously adapted to capture skin irritation with tenderness from the sun occurring in darker skin types (n = 350). By self‐reported responses and spectrophotometry assessment of constitutive pigmentation, adapted Fitzpatrick skin types (FST) ranged from skin type I–IV in the Mexican American participants and from II to V in the Puerto Rican participants. The objectively measured proportion of adapted FST II skin type was greater than commonly perceived and demonstrated that many Latinos do indeed have sun‐sensitive skin.     

Epidermis generated in vitro: practical considerations and applications

The technology for culture of epidermis is one of the most advanced to date for generation of a tissue in vitro. Cultured epidermis is already used for a number of applications ranging from use as a permanent skin replacement to use as an organotypic culture model for toxicity testing and basic research. While simple epidermal sheets have been grafted successfully, more advanced models for skin replacement consisting of both dermal and epidermal components are in development and being tested in a number of laboratories. One of the most advanced in vitro models is the living skin equivalent, an organotypic model consisting of a collagen lattice contracted and nourished by dermal fibroblasts overlaid with a fully formed epidermis.     

The role of human immortal skin keratinocytes-acellular dermal matrix scaffold in skin repair and regeneration

In this study, we aimed to investigate the phenotypic characteristics of human immortal skin keratinocytes (HaCaT) cells and the role of acellular dermal matrix (ADM) in coculture system of HaCaT cells and ADM. Flow cytometry was used to examine the cluster of differentiation (CD) makers of HaCaT cells. Apoptosis analysis was applied to detect the apoptosis rate of HaCaT cells. Morphological observation of ADM isolated from the reticular layer of Sprague-Dawley rat dermis was utilized to evaluate the morphological structure of ADM. Methylthiazolyl tetrazolium (MTT) assay and morphological experiments were further used to confirm the scaffold role of ADM in HaCaT cells. A wound-healing mice model accompanied by HaCaT-ADM scaffold transplantation was performed to further verify the function of HaCaT-ADM scaffold. Our results showed that CD71, CD49f, K19, and CD29 were highly expressed in HaCaT cells, and the percentage of apoptosis cells was significantly increased, which represented that HaCaT cells had much stronger capacities of adhesion and proliferation than normal human keratinocytes. Additionally, the morphological structure of ADM presented many natural microbores, which made cells rapidly grow on ADM. The results exhibited that the HaCaT cells indeed promptly proliferate on ADM and easily grow into the microbores of ADM. Finally, an in vivo experiment further confirmed that the transplantation of the HaCaT-ADM scaffold into the dorsal skin of a wound-healing mice model could gradually repair the injured wound. Thus, these findings indicated that HaCaT cells might be as seed cells to develop skin tissue engineering and the HaCaT-ADM scaffold might be a better candidate to promote skin repair and regeneration.     

负压创面治疗技术对皮肤移植成活的临床观察及实验研究

目的：采用负压固定移植皮片方法,观察负压创面治疗技术（negative-pressure wound therapy,NPWT）对游离皮片成活的影响,初步探讨微血管形成与皮肤成活之间的关系。方法：采用回顾性研究的方法,对65例皮肤缺损的患者,根据皮肤移植术后皮片固定方法的不同,分为两组,其中Ⅰ组为NPWT治疗组,有35例患者,刃厚游离皮片移植术后行创面负压吸引治疗;Ⅱ组为常规治疗组。有30例患者,刃厚游离皮片移植术后用打包或加压包扎的方式固定。Balb／c小鼠20只,按皮片移植后不同固定加压方式,分为实验组：负压创面治疗技术使用组（10只）,对照组：打包加压组（10只）,于皮片移植术后第5天,大体观察移植皮片颜色、有无水疱、有无皮下积液及质地,计算并比较皮片成活率,以免疫组化染色标记毛细血管内皮,检测皮片中微血管情况。结果：临床观察表明：Ⅰ组术后皮片成活时间平均较Ⅱ组缩短,有统计学差异（P〈0．01）,Ⅰ组术后住院治疗时间平均较Ⅱ组缩短5天,有统计学差异（P〈0．01）,Ⅰ组术后抗生素费用、换药次数及换药费用较Ⅱ组减少,有统计学差异（P〈0．01）。动物实验结果表明：术后第5天,实验组小鼠移植皮片中微血管增生较对照组明显增多（P〈0．05）。结论：与常规打包或加压包扎固定皮片的方式相比,负压创面治疗技术的应用可以缩短皮片成活时间,缩短患者住院治疗时间,减少抗生素的使用及换药次数,促进移植皮片中毛细血管增生,提高皮片成活率。     

The impact of skin colour on human photobiological responses

Terrestrial solar ultraviolet radiation (UVR) exerts both beneficial and adverse effects on human skin. Epidemiological studies show a lower incidence of skin cancer in people with pigmented skins compared to fair skins. This is attributed to photoprotection by epidermal melanin, as is the poorer vitamin D status of those with darker skins. We summarize a wide range of photobiological responses across different skin colours including DNA damage and immunosuppression. Some studies show the generally modest photoprotective properties of melanin, but others show little or no effect. DNA photodamage initiates non‐melanoma skin cancer and is reduced by a factor of about 3 in pigmented skin compared with white skin. This suggests that if such a modest reduction in DNA damage can result in the significantly lower skin cancer incidence in black skin, the use of sunscreen protection might be extremely beneficial for susceptible population. Many contradictory results may be explained by protocol differences, including differences in UVR spectra and exposure protocols. We recommend that skin type comparisons be done with solar‐simulated radiation and standard erythema doses or physical doses (J/m²) rather than those based solely on clinical endpoints such as minimal erythema dose (MED).     

Synthesis and biological evaluations of oleanolic acid indole derivatives as hyaluronidase inhibitors with enhanced skin permeability

Oleanolic acid (OA) is a natural cosmeceutical compound with various skin beneficial activities including inhibitory effect on hyaluronidase but the anti-hyaluronidase activity and mechanisms of action of its synthetic analogues remain unclear. Herein, a series of OA derivatives were synthesised and evaluated for their inhibitory effects on hyaluronidase. Compared to OA, an induction of fluorinated (6c) and chlorinated (6g) indole moieties led to enhanced anti-hyaluronidase activity (IC₅₀ = 80.3 vs. 9.97 and 9.57 µg/mL, respectively). Furthermore, spectroscopic and computational studies revealed that 6c and 6g can bind to hyaluronidase protein and alter its secondary structure leading to reduced enzyme activity. In addition, OA indole derivatives showed feasible skin permeability in a slightly acidic environment (pH = 6.5) and 6c exerted skin protective effect by reducing cellular reactive oxygen species in human skin keratinocytes. Findings from the current study support that OA indole derivatives are potential cosmeceuticals with anti-hyaluronidase activity.     

皮肤类器官的构建、功能及其应用研究进展

皮肤类器官作为一种新型的类器官模型,不仅能高度模拟皮肤组织的生理结构和功能,更好地在不同体外环境下还原较真实的皮肤生态,还可以应用于皮肤发育研究、皮肤疾病病理研究及药物筛选等领域。在干细胞研究中,皮肤类器官模型可以在特殊的生境下对具有特定功能的皮肤细胞及其附属物进行重建和改造,以弥补现有体外皮肤模型在结构、功能等方面的不足。基于此,皮肤类器官将会在皮肤再生、组织修复、药物筛选及医学美容等方面扮演越来越重要的角色。本文详述了皮肤类器官构建中所参与的细胞来源及近年来的应用,并对未来皮肤类器官的发展与优化做出了展望。     

皮肤模型与微针穿刺性能评价的研究

微针阵列作为新型透皮给药技术,受到广泛关注。通常以刺入力、刺入率和刺入深度来评价微针刺入皮肤的程度和效率。皮肤是其性能评价的基础。皮肤的物理特性主要由角蛋白丝、胶原纤维、弹性纤维和皮下组织综合决定,并且从厚度、弹性、硬度和韧性等维度反映其对微针刺入的影响。机械的、渗透的、组织的和屏障的等皮肤模型被用于解读和模拟真实皮肤的该方面功能。同样,通过皮肤力学分析后建立的包括本构模型在内的各种皮肤力学模型也从物理维度解析皮肤的力学特征。真实皮肤具有复杂性,存在差异性大、不易获取和储存,以及伦理等问题,而皮肤模型可在一定程度上代替真实皮肤辅助微针递送系统设计、开发和性能评价。本文系统回顾分析了皮肤组织的物理特性、各种皮肤模型的制备及特点、真实皮肤和模拟皮肤在评价微针穿刺性能方面的应用,为开发及建立合适的皮肤模型提供借鉴。     

Evidence for a rhesus monkey model of asymptomatic tuberculosis

Rhesus monkeys (RM) were inoculated intrabronchially with graded doses of Mycobacterium tuberculosis (MTB) strains Erdman and H37Rv in an effort to produce a model of asymptomatic tuberculosis infection. Erdman strain produced active disease within 7-11 weeks regardless of dose. Low doses of H37Rv resulted in asymptomatic infections; high doses produced active disease within 11 weeks. Over a 4-month period of post-inoculation study, MTB culture-filtrate protein (CFP)-stimulated bronchoalveolar lavage cells (BALC) and blood mononuclear cells (PBMC) from monkeys with active disease (30 cfu Erdman-inoculated) or asymptomatic infection (200 cfu H37Rv-inoculated) produced similar significant quantities of mRNA encoding for IFN-gamma or TNF-alpha, but insignificant quantities of IL-4 mRNA. Differences were observed in antigen-induced in vitro blastogenic responses and serum anti-lipoarabinomannan (LAM) antibody responses in animals with active compared with asymptomatic MTB infections. The results indicate that RM are a good model for the study of asymptomatic tuberculosis infections using low doses of H37Rv.     

Reproductive parameters and paracallosal skin color changes in captive female Guinea baboons,Papio papio

Reproductive data are presented for female Papio papio housed in the Zoological Park of Paris and are compared with previously published data from free‐ranging populations of other baboon species. The results indicate similar intermenstrual intervals and durations of sexual swelling. Sexual swelling and pregnancy are accelerated in captivity, while postpartum amenorrhea and interbirth interval are reduced. Interbirth intervals in P. Papio were short, approximately 13 months in the case of viable, surviving infants and approximately 11 months in the case of stillbirth or neonatal mortality. The shorter interval may represent the lower physiological limit, and the generally shorter interbirth interval reported here may be explained by lower stress and reduced maternal investment costs in the captive environment. Paracallosal skin color variations during the menstrual cycle were influenced by parity, but sexual swelling patterns were not. The paracallosal skin changes might be used by males as a cue to females' reproductive status. Am. J. Primatol. 47:67–74, 1999. © 1999 Wiley‐Liss, Inc.